Novel process for preparing an absorbent article

ABSTRACT

The present invention is directed to a novel process for preparing an absorbent article, wherein the process comprises providing a first sheet layer ( 2 ); conforming said first layer on a first roll C 2 , whereby longitudinal corrugations are formed on the layer; conforming said corrugated layer ( 2 ) on a second roll C 3 , whereby a pattern of pockets ( 4, 4   a ) is obtained; providing a pre-metered amount of SAP particulate material ( 6 ); providing a second sheet layer ( 7 ) material and affixing it for sandwiching with the first sheet layer; and finishing the absorbent article.

RELATED APPLICATIONS

The present application claims priority from EP11196129 filed 29 Dec.2011, EP11196130 filed 29 Dec. 2011, EP11186336 filed 24 Oct. 2011 andEP11186337 filed 24 Oct. 2011.

FIELD OF THE INVENTION

The present invention is directed to a novel process for preparing anabsorbent article. More specifically, the present invention is directedto a process for filling super absorbent polymer into recesses formed ona supporting, travelling layer.

BACKGROUND OF THE INVENTION

Absorbent articles are known and commonly used in personal careabsorbent products such as diapers, training pants, sanitary napkins,incontinence garments, bandages and the like. The invention also relatesto a process for making said article.

Nowadays, the absorbing element in the article is comprised of highabsorbency materials such as superabsorbents (Super AbsorbentPolymers—SAP-), which form the diaper's absorbent core.

While the SAP has many advantages, it is also difficult to dose, giventhe fact that SAP is available as a powder. The problem is not acute foruniform layers dispensing devices, but becomes very relevant when SAPpatterns are required.

EP-A-1621166 discloses a process for producing absorbent corestructures, comprising the steps of:

-   -   providing a carrier material;    -   providing a support for said carrier material, the support        having a support pattern;    -   providing a carrier material holding means (especially vacuum        applying means);    -   positioning said carrier over said support means, whereby said        carrier contacts said support;    -   providing a pre-metered amount of SAP particulate material;    -   providing a cover material for sandwiching with the carrier; and        wherein    -   said carrier material is supported only in the region of the        support pattern of the support means;    -   said carrier material is deformed by said carrier holding means        such that indentations are formed in the unsupported regions:    -   said SAP particulate material being transferred to said carrier        material into said indentations thereby forming a primary        pattern of particulate material.

EP-A-1621167, a companion application of the above EP-A-1621166,discloses a process for producing absorbent core structures, comprisingsubstantially the same steps, and wherein the process comprises thesteps of:

-   -   providing a SAP particulate material;    -   providing a transfer device for receiving said SAP particulate        material in a receiving region and transferring it to an        discharging region;    -   said transfer device comprising a first pattern forming means.

In the above processes, the pattern is formed by the indentations formedin the unsupported regions. This provides for a poor uniformity, and thedepth of the clusters formed by the indentations is rather limited.Also, the entire pattern is formed during one operation. The dispensingof the SAP particulate material makes use of a feeding hopper, thisbeing derived from the helio-cylindrical printing system. The volume ofthe delivered SAP cannot be changed, while the SAP particulate materialcan vary because of different suppliers. Any change requires a change inthe engraving of the dispensing roll. Further, high speeds are notpossible with such systems. Last, in order to have a dosing that isreliable, it is necessary to compact the SAP in the discharging regions,which does not facilitate the complete release into the clusters andprovides for attrition and shearing forces applied by the hopper to theSAP, which is a fragile material and subject then to degradation.

The above techniques thus still do not completely solve the problems ofthe distribution of SAP in cavities formed in the absorbent article.

Consequently, there is a need for an improved process for formingliquid-absorbing article containing SAP where the SAP is distributedaccording to a given pattern, and where the SAP is delivered in a fastand reliable manner.

SUMMARY OF THE INVENTION

The invention thus provides a process for manufacturing an absorbentarticle (1), said article comprising:

-   -   a first sheet layer (2) presenting an array of absorbent        receiving pockets (4, 4 a);    -   masses (6) of superabsorbent material, which masses are placed        in said absorbent receiving pockets (4, 4 a);    -   a second sheet layer (7) placed on top of the first layer; said        process comprising the steps of    -   providing a first sheet layer (2);    -   conforming said first layer on a first roll C2, whereby        longitudinal corrugations are formed on the layer;    -   conforming said corrugated layer (2) on a second roll C3, said        second roll C3 comprising recesses (91 a, 91 b, 91 c)        corresponding to the array of absorbent receiving pockets (4, 4        a), whereby a pattern of pockets (4, 4 a) is obtained;    -   providing a pre-metered amount of SAP particulate material (6);    -   providing a second sheet layer (7) material and affixing it for        sandwiching with the first sheet layer;    -   finishing the absorbent article, and    -   said step of conforming on a first roll C2 being obtained by        friction of the    -   sheet layer (2) on the corresponding corrugated surface of said        roll C2.

According to one embodiment, the process further comprises unrollingsheet layer (2) from roll C1, where roll C2 has a rotating speed(peripheral) that is 5 to 20% above the speed of roll C1.

According to one embodiment, the process further comprises the step ofunstressing the sheet between rolls C2 and C3.

According to one embodiment, the roll C1 has a rotating speed which ishigher than the rotating speed of roll C3, where roll C1 has a rotatingspeed (peripheral) that is 5 to 20% above the speed of roll C3.According to one embodiment, the process further comprises the step ofpinching the sheet between roll C2 and counter roll CC2, where the rollC2 and counter roll CC2 have grooves (71 a, 71 b, 71 c, 71 d) and ribs(81 a, 81 b, 81 c, 81 d) cooperating with each other.

According to one embodiment, the step of forming the pockets comprisesholding the layer (2) and/or (7) into the second roll C3 by applyingvacuum.

According to one embodiment, said pre-metered amount of SAP material isdelivered from a delivering unit placed above roll C3, whereby thepre-metered amount of SAP is filled in a pattern of pockets.

According to one embodiment, the process further comprises the step of:

-   -   providing bonding beads (5), preferably adhesive beads, between        the pockets.

According to one embodiment, the process further comprises the step of:

-   -   providing adhesive layers (3) and/or (8) between the first and        second layers, whereby said layers are bonded.

According to one embodiment, the process further comprises the step of:

-   -   calendering into the absorbent article (1).

According to one embodiment, the sheet layer (2) and/or (7) is/arenon-woven.

According to one embodiment, the sheet layer (2) is impervious toliquids and the sheet layer (7) allows penetration of liquids into themasses of superabsorbent material.

The process is especially suited for manufacturing a diaper, trainingpant, sanitary napkin, incontinence garment or bandage comprisingmanufacturing an absorbent article according to any one of the precedingclaims, and converting said article into said diaper, training pant,sanitary napkin, incontinence garment or bandage.

The invention thus allows the formation of arrays of pockets at twodistinct locations in the process. Unlike the prior art recited above,the respective walls of the pockets are formed in two separate steps inthe process. This allows a better shaping of the pockets, and control oftheir geometry. Also, pockets of large dimensions, including pocketswith large depths can be easily manufactured.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 represents the formation of the absorbent article of theinvention.

FIG. 2 represents a schematic illustration of the top view of anabsorbent article according to the invention

FIG. 3 represents an overall view of the process of the invention forthe manufacture of the article.

FIG. 4 represents the bottom layer supply step FIG. 5 represents theadhesive layer (3) distribution step.

FIG. 6 represents the forming of the sheet layer (2) onto roll C2

FIG. 7 represents an enlarged view of roll C2.

FIG. 8 represents the beads deposition step.

FIGS. 9 a and 9 b represent the roll C3 for two different embodiments ofthe invention

FIGS. 9 c and 9 represent the respective discs, corresponding to FIGS. 9a and 9 b.

FIG. 10 represents the SAP distribution step and the calendering step,as well as the optional ADL deposition step.

FIG. 11 represents the finishing step.

FIG. 12 represents a perspective view of roll C2 and counter roll CC2.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention is now disclosed in more details below, in a non-limitingmanner.

Reference is made to FIG. 1 which discloses the formation of theabsorbent article of the invention according to one embodiment.

In an initial step, a first sheet layer (2) is provided. This firstlayer will serve as the bottom layer. It may be impervious to liquids,but this is not necessary in case of the presence of an imperviousbacksheet in the diaper for example.

This layer then receives a layer of adhesive (3). This adhesive istypically a hot-melt, as will be disclosed in more details below. Theadhesive may be present on the entire surface or only at the vicinity ofthe sealed area. It is preferred that the adhesive be present on theentire surface (in a continuous or discontinuous manner). With thisembodiment, the adhesive will receive the SAP and will adhere to it sothat most of the SAP will be caused to adhere to the surface of thesheet layer. This will improve the SAP position and further prevent SAPfrom slipping within the disposable diaper.

The sheet layer (2) with the adhesive layer (3) is then formed into thedesired shape. Different techniques may be used to form the shape of thepocket (4, 4 a), as will be disclosed in more details below. In theembodiment that is disclosed, the step is disclosed in relation with themachine direction, forming bands, a specific step with respect to thetransverse direction is applied later on.

Adhesive beads (5) (also known as adhesive ropes) are then applied at alocation between the pockets (4, 4 a) previously formed, as illustratedin FIG. 2, which is a top view of an absorbent core with pockets inrectangular shape and beads in the machine direction (MD) and transversedirection (TD). Standard techniques are used.

The beads ensure structural strength by keeping the sheet layers bondedduring use.

The step of forming the pockets in the transverse direction is thenperformed; this step is optional but preferred. The step of adhesivebeads deposition can be performed before or after the step of formingthe transverse direction forms for the pockets. It may also be performedat about the same time.

The pockets thus formed can have various shapes and forms. For example,the pockets can be rectangular or square in shape with varying lengthsof their respective sides. For example the length may vary from 10 mm×10mm to 10 mm×80 mm, including 20 mm×20 mm to 20 mm×60 mm or 20 mm×20 mmto 40 mm×40 mm or 20 mm×40 mm with varying shapes, in any direction. Thedepth of the final pocket depends e.g. on the mass of SAP material to befilled in. For example for baby diapers a depth from 1 mm to 5 mm (oncefinally formed, i.e. calendered) may be preferred. Any other desiredgeometric forms and patterns are conceivable. Particular preference isalso given to the application of one or more continuous strips inmachine running direction, the strips running parallel to one another.

Thus a longitudinal pocket is possible; in this case the pocket will beelongated, e.g. from 10-80 mm×100-400 mm.

The SAP is then placed in the thus-formed pockets, using an appropriatedosing device, as will be disclosed in more details below.

The second sheet layer (7) receives first an adhesive layer (8). Thesecond sheet layer is typically water-permeable so as to allow thefluids to penetrate through and reach the SAP. This second sheet willtypically serve as the top layer. The adhesive layer will not becomplete or will be porous, so as to allow transfer of fluid through thesheet layer. The adhesive layer (8) is optional and may be omitted.

The second sheet layer (7) with the adhesive layer (8) is then affixedonto the first sheet layer (2) with the pockets (4, 4 a) containing theSAP (6) and bearing the beads (5). This is done in an area (9) in thevicinity of the beads (5)

Calendering is then performed on the sandwich thus formed, ensuring thebonding of the two sheet layers.

For example, a pressure sensitive adhesive is applied directly on thebottom layer of the assembly (a nonwoven). The same adhesive is alsoapplied directly on the top layer of the assembly (a nonwoven. The toplayer was mounted on the bottom layer and pressed using a pressure roll.In another embodiment, the previous assembly was reiterated butinserting between the adhesive-coated top and bottom layers, a bead ofadhesive. The same method is used to create the assembly, making surethat the adhesive bead is placed in the middle of the pressed laminate.

SAP is maintained in a very efficient way in the pockets formed in theinvention, being prevented from slipping and/or aggregating at one placein the article.

The steps for manufacturing the article of the invention and the variouselements thereof are disclosed in more details below.

The SAP that is used in the invention is any product that is able toabsorb water to a significant amount. A typical SAP will absorb waterfrom 10 to 50 times its dry volume, typically from 20 to 40 times (theratio can be higher if expressed in terms of weight ratios). Forexample, 15 g of SAP may retain 400 cc of fluid (tested as 4 successivewettings, 4×100 cc). BASF is exemplary of a company supplying SAP. SAPis generally available as a powder, with varying particle size (e.g.more than 60% of the particles flow through a mesh from 100 μm to 850μm). Typically SAPs are (meth)acrylic polymer, especially alkali metalsalts of polyacrylic acids. Core-shell polymers can be used, where theinner is absorbing and the outer is an osmotic membrane. SAPs are wellknown for the skilled man.

The production of fluid-absorbing polymer particles (Super AbsorbentPolymers—SAP-) is likewise described in the monograph “ModernSuperabsorbent Polymer Technology”, F. L. Buchholz and A. T. Graham,Wiley-VCH, 1998, pages 71 to 103.

The SAP may also be the one disclosed in WO2010/133529, from page 6 line1 to page 15 line 16, incorporated herein, by reference.

The SAP load may vary within broad limits. For example, for a babydiaper, the amount of SAP usually used is from 8 to 20 g, preferablyfrom 11 to 18 g, more preferably from 12 to 15 g.

The invention also uses sheet layers, one typically as a bottom layerand one typically as a top layer. Typically, both sheets are non-woven.Non-woven can be manufactured using different technologies and one cancite staple non-woven, spunbonded non-woven, spunlaid non-woven,air-laid non-woven, and the like. Bonding can be mechanical (e.g.entanglement), thermal, ultrasonic, chemical, and the like. Non-wovenare well-known for the man skilled in the art. The non-woven used can bestandard or can be structured, and can also be already embossed ifneeded.

The non-woven can be pervious to liquids or impervious to liquids. Theskilled man will select the fibers to be used to match the requirements.Hydrophilization of fibers is known to render fibers suitable for themanufacture of liquid-pervious non-woven.

Fibers can be customary synthetic or semi-synthetic fibers, such aspolyesters, polyolefins and rayon, or customary natural fibers, such ascotton. In the case of nonwoven materials, the fibers can be bonded bybinders such as polyacrylates. Preferred materials are polyester, rayon,polyethylene and polypropylene. Examples of liquid-pervious layers aredescribed, for example, in WO 99/57355 A1 and EP 1 023 883 A2.

Examples of liquid-impervious layer are layers consisting typically ofhydrophobic polyethylene or polypropylene; other material can be usedsuch as polyester and polyamide.

Multilayer structures are also possible, so as to provide for a specificaspect or feel on one side of the sheet and specific properties on theother side, e.g. with respect to adhesion.

References EP1609448, as well as US2008/0045917 provide for disclosureof such non-wovens.

The top layer will be permeable to liquids, so as to allow the liquidbeing entrapped by the SAP. A possible non-woven for the top layer willbe one with polyethylene or polypropylene fibers having received ahydrophilization treatment, or rayon or any other suitable fibers. TheLivedo reference above contains a disclosure of possible top layers. Thesurface weight can vary between wide ranges, such as from 5 to 100 g/m²,preferably from 10 to 50 g/m².

The bottom sheet layer will be impervious to liquids, as is usually thecase, but not necessarily. A possible layer is a non-woven layer. Apossible non-woven for the bottom layer will be one with polypropyleneor polyester fibers, as is well-known for the skilled man. The Livedoreference above contains a disclosure of possible bottom sheet layers.The surface weight can vary between wide ranges, such as from 5 to 100g/m², preferably from 10 to 50 g/m². The bottom sheet layer will alsohave a porosity to air that will be controlled. This will assist informing the pockets and filling in the SAP, as will become more apparentbelow.

The adhesives used in the invention are known for the skilled man. Thefirst type of adhesive is used for the beads. The adhesive for the beadsis typically a hot-melt. It may be typically a PSA (Pressure SensitiveAdhesive). The preferred adhesive is thus a HMPSA. Exemplary HMPSA thatmay be used for the beads is an SBS-based adhesive with hydrogenatedhydrocarbon resins and naphthenic oil. The process for adhesivedeposition is known to the skilled man, and the lines can be continuousor broken, preferably continuous. The linear weight is from 0.1 to 5g/linear meter.

Beads can be present in the machine direction (MD), transverse direction(TD) or both. The beads ensure geometrical stability of the absorbentarticle. The beads also ensure a draining function. The liquid canmigrate within the thickness of the sheet layer esp. the non-woven. Atthe beads level, the liquid will be guided along the pathways defined bythe beads, and draining pathways will then be defined. This ensures amore uniform distribution of the fluid over the entire absorbentarticle.

Similar adhesives are used for adhesives layers (3) and (8) (ifpresent). The adhesives may not be the same for the top layer and thebottom layer. The adhesive may be deposited using techniques known tothe skilled man. The coating can be total or partial (multi lines, multidots, according to specific patterns, MD, TD, spiral spray, porouscoating, foam coating, and the like). The adhesive, if used on the toplayer, will be such that fluids will be able to go through the toplayer. Hence, the coating for the top layer is usually an open coating.The surface weight will usually be from 5 to 60 g/m2, preferably from 10to 20 g/m2. Adhesives used with the sheet layers (beads or deposited onthe sheet layer) are preferably not hydrosoluble.

Hot melts are preferred, especially Pressure Sensitive Adhesives (PSA,especially HMPSA).

Very generally speaking, and without this being limiting, the hot meltadhesives comprise:

(a). Polymers such as EVA, PE, PP, EEA (ethylene ethyl acrylate) and thethermoplastic elastomers or rubbers which are (block) styrene copolymerssuch as SIS, SIBS, SEPS, SBS, SEBS, or butadiene-based polymers or, yetagain, ethylene-propylene copolymers such as EPR, and Olefin BlockCopolymer OBC. A chemical modification such as maleic anhydridemodification is possible.

A typical average molar mass in weight MW is between 60 kDa and 400 kDafor the polymer.

They can make up from 10 to 80%, preferably 15 to 40% of the formulationand their purpose is to provide: mechanical strength, flexibility,barrier properties, brilliance and viscosity control.

(b). tackifying resins which can be polar or non-polar resins. Polarresins can be (i) rosins of natural or modified origin, such as forexample the rosin extracted from the gum of pinewood, their polymerized,dimerized, dehydrogenated, hydrogenated derivatives or esterified bymonoalcools or polyols like glycol, glycerol, pentaerythritol; (ii)terpenic resins generally resulting from the hydrocarbon polymerizationterpenic in the presence of catalysts of Friedel-Crafts like themono-terpene (or pinene), the alpha-methyl styrene, and possiblymodified by phenol action. Non-polar resins can be (iii) resins obtainedby hydrogenation, polymerization or copolymerization (with an aromatichydrocarbon) of mixtures of unsaturated aliphatic hydrocarbons resultingfrom oil cuts; (iv) terpenic resins generally resulting from theterpenic hydrocarbon polymerization in the presence of catalysts ofFriedel-Crafts such as for example mono-terpene (or pinene), copolymerscontaining natural terpenes, for example styrene/terpene, thealpha-methyl styrene/terpene and the vinyl toluene/terpene.

Tackifying resins can be natural (rosin esters, terpene orterpene-phenolic esters), or oil-based, aliphatic or aromatic.

They make typically up from 10 to 80%, preferably 30 to 60%, of theformulation. They increase the hot tack, adherence and control cohesion.

(c). Paraffins and waxes, which can make up from 0 to 20% of theformulation. They play a role in providing barrier, rigidity and hotmelt hardness properties.

(d). Plasticizers such as oils which can make up some 0 to 30% of theformulation. They control hot melt flexibility and viscosity.

(e). Anti-oxidants which may make up from 0.2 to 2% of the formulation.They stabilize the components when hot and when cold.

(f). Fillers which may make up part of the formulation when particularproperties are desired such as UV-resistance (oxidation resistance),flame proofing, anti-allergy properties, rheology modification, etc.

An hot-melt may have the following composition: 15 to 40% thermoplasticpolymer, 30 to 60% tackifying resin, 30% or lower of other constituents:plasticizing oil, anti-oxidation agents, additives etc.

Residual tack can be controlled by adjusting the ingredients and theformulation.

An adhesive may also be used with the SAP. This may assist in reducingthe SAP movements. This can be, as disclosed above an HMA, HMPSA. It mayalso be water based (WB), and for example it can be a WBPSA. Theadhesive used together with the SAP can be hydrosoluble. This adhesivecan be deposited at the same time the SAP is placed in the formedpockets. This embodiment will allow a tighter holding of the particlesor grains of SAP, which is beneficial for the process and/or design.

With reference to FIG. 3, an overall view of the process is provided. InFIG. 3 are represented the rolls C1, C2, C3, C4, C5 and C6, andassociated slender rolls for rolls C1, C3 and C6. Nip points A, B, C Dand E, corresponding respectively to the nip between rolls C1 andslender roll, C3 and C4, C3 and slender roll, C3 and C5, and C6 andslender roll are also shown in FIG. 2. Are also represented sheets (2)and (7) when supplied from appropriate sources. Each sub-step of FIG. 1can also be found in a corresponding manner in FIG. 3. Each step willthen be disclosed in a more detailed manner below. One will understandthat the optional steps in FIG. 1 are similarly optional in FIG. 3.

With reference to FIG. 4, the initial bottom layer supply step isdisclosed. Sheet layer (2) is unrolled under mild tension up to a nippoint #A between roll C1 and associated slender roll. Roll C1 ispreferably smooth and comprises for example a rubber sheath (or sleeve).

With reference to FIG. 5, the sheet layer (2) (bottom layer) willreceive an adhesive layer (3). This adhesive can be HMPSA and isrepresented by the deposition of glue G1. This takes place while thebottom layer is on roll C1, after nip point A. This adhesive will servethe purpose of retaining as much as possible the SAP that will bedistributed in the pockets at point #B (see below). The adhesive coatingis performed using standard techniques, as indicated above. The surfaceweight of the adhesive layer (3) is standard in the art. In oneembodiment, the adhesive is deposited as a foamed product. A foamedproduct will offer, for a given thickness, savings in adhesive amount, ahigher tackiness, a lower cohesion (entrapping of SAP), and a lower flow(SAP particles coating should be avoided since their specific surface isone driving factor for the liquid absorption).

With reference to FIG. 6, the sheet layer (2) (bottom layer) is formedonto a roll C2 so as to impart the lengthwise profile of the pockets.Roll C1 has a rotating speed which is higher than the rotating speed ofroll C3 (peripheral rotating speed is 5 to 20% higher, preferably 10 to20%). The difference in rotating speed allows material to be present forforming the vertical walls of the pockets. Roll C2 will have a rotatingspeed slightly above the speed of roll C1 (peripheral rotating speed is5 to 20% higher, preferably 10 to 20%) so as to generate a tensionnecessary for the forming. The friction being higher in the upper partof roll C2 will also ensure tensioning the bottom layer duringdeposition of the adhesive beads (below). Roll C2 can receive a non skidcoating.

In FIG. 7, the roll C2 has grooves 71 a, 71 b, 71 c, 71 d. Each groovehas a valley, represented here with a square shape, but tapered valleysare possible, and the angles can be smoothed if desired. Is representedvalley 72 a corresponding to groove 71 a. A corresponding peak 73 a isrepresented, between two adjacent valleys. The web that is obtainedafter roll C2 hence exhibits ribs or corrugations. The web will matchthe groove due to the difference in friction between the top and thebottom of the grooves and the difference in winding speeds. Thedifference in winding speeds between the different rolls allows materialto match the inner of the grooves. Roll C3 has the lowest winding speed,then roll C1 has an intermediate winding speed and finally roll C2 isthe roll having the greatest winding speed among the three. The width ofthe web is reduced due to the formation of ribs/corrugations in thegrooves; the difference in rotating speeds provides for a relaxation ofthe web tension and allows for such formation. The sheet layer (2) (withthe adhesives (3) and/or (5)) is unstressed between rolls C2 and C3,where roll C3 has a rotating speed below the one of roll C2, aspreviously indicated. The difference in rotating speeds between rolls C2and C3 is dictated by the amount (or length) of sheet layer that isnecessary to form the other part of the vertical walls of the pockets.The two nip points #A and #D (calendering, see below, nip point #D isnot represented on FIG. 6) will act as fixed points to impart thegeometry to the sheet between the two nip points.

Roll C2 can be obtained by stacking discs of varying thicknesses anddiameters (corresponding to width and depth of the pockets). This allowschanging rapidly the geometry of the article without the need to revertto a complete change of set of rolls.

With reference to FIG. 8, the beads deposition is disclosed. Lengthwisebeads are deposited using standard techniques. Because roll C2 has anadapted speed, the tension on the outer surface is suited for receivingthe adhesive beads. The beads may not need to be necessarily linear, orcontinuous. They can be in the form of zigzags, and can be as dots.Beads deposition takes place on the sheet at locations corresponding to,or close to, the peaks 73 a.

An alternative embodiment is one where the adhesive beads are replacedby another bonding process. As bonding process, one can use theheat-sealing, the ultrasound sealing, sewing, carding the two non-woventogether. Bonding without adhesives is carried out generally after thecalendering step.

With reference to FIG. 6 (see above), the pockets formation isdisclosed, where the pockets are formed mainly by roll C3. In a mannersimilar to the forming according to MD (Machine Direction), the formingof the pockets in the TD (Transverse Direction) is carried out using aroll C3 formed from stacking discs with selected geometry, forming amatrix.

With reference to FIG. 9 a, a roll C3 is disclosed which is a matrix.The bottom part of the recesses (91 a, 91 b, 91 c) in the roll C3 isequipped with holes, allowing applying a vacuum. Applying a vacuum willserve attracting the sheet layer so as to conform it to the shape of thematrix, to define the pockets. The air porosity (Gurley porosity) of thebottom layer non-woven will be adapted such that the vacuum applied inthe central part of the roll C3 is sufficient to press the sheet againstthe roll by suction. The applied vacuum will also serve when the SAP isdistributed into the pockets thus formed (see below). The applied vacuumcan be obtained with an inner drum or mandrel inserted into the roll,which can be segmented so as to apply vacuum only to those part of theroll in need thereof. The sector with the vacuum can thus representbetween 30° and 180°, preferably between 60° and 120°.

A vacuum sector can be of the type disclosed in the prior art documentsmentioned above, see EP-A-1621166 and EP-A-1621167. Roll C3 can bevaried in dependence on the desired shape or geometry of the pockets.

FIG. 9 b represents a roll C3 with elongated shapes, rather than matrixshapes.

The roll C3 can be obtained in a manner similar to roll C2, i.e. byusing discs that are stacked on an axis. FIGS. 9 c and 9 d represent therespective discs, corresponding to FIGS. 9 a and 9 b.

With reference to FIG. 10, is disclosed the distribution of the SAP. SAPis distributed from roll C4, which is counter-rotating with respect toroll C3. Rotating speeds of rolls C3 and C4 are adapted one to theother. The two rolls are usually not in contact, a small gap existingbetween the two, so as to adapt for varying thicknesses for the bottomlayer (2). One possible technique for dispensing SAP is the onedisclosed in document US7744713, incorporated herein by reference.Vacuum being applied in the forming roll, this will also assist the SAPto be kept in place (with the Gurley porosity of the bottom layer beingadapted to let the vacuum have an effect on holding in place the SAP).

With reference to FIG. 10 is also disclosed the bringing into contact ofthe top layer (sheet layer (7)). The top layer is displayed facing thebottom layer at a nip point #C, before calendering. Point #C ispreferably as close as possible to nip point #B, so as to avoidpolluting adhesive parts (if any) with the powdery SAP. The top layer(7) is brought under tension on the top of the pockets formed before andis tensioned by passing over a slender roll (which may have a bananashape). Tension is preferably applied to as to minimize the effect ofthe vacuum on the top layer to be applied (tension will avoid waves thatcould otherwise form due to the vacuum). The slender roll may alsocomprise rigs, so as to form a top layer with pleats within thethickness (to provide for further expansion).

With reference to FIG. 10, is also disclosed the calendering step. Apressure is applied between rolls C3 and C5 to proceed with the fixingof the top layer onto the bottom layer, whereby closed pockets (4 a) areformed.

Is also represented as a further, optional, embodiment, the providing ofthe acquisition distribution layer ADL (11). This layer is supplied atnip point #C so as to be formed into a sandwich at that point. This ADLwill preferably receive adhesives on both faces, but can also be fixedusing any of the bonding system discussed above.

With reference to FIG. 11, is disclosed the finishing step. Thecompacting is carried out during winding under tension of the finishedproduct. A pressing roll C6 is used to impart pressure at point #Eduring winding.

Two optional steps can be present (not shown).

The first optional step is the coating of the top layer (7) with anadhesive layer (8). Coating is an open coating, so as to ensure that thetop layer will keep breathability and liquid uptake properties. Coatingcan be carried out as porous coat, spiral-spray coating, multi lines,pattern coating, and the like. Coating methods are well known to theskilled man.

The second optional step is the spraying of adhesive for holding and/oragglomerating the particles of SAP. This spraying can be performed withan airless technique (low pressure) or air-mix. This would be appliedonto the SAP particles once deposited into the pockets, substantiallyimmediately after the SAP has been distributed from roll C4 (and beforethe top layer is affixed).

While the above disclosure has been given with the bottom layerreceiving the SAP, it is possible, albeit less preferred, to invert thetwo sheet layers in the apparatus described above.

When beads are present in both the MD and TD, the process disclosedabove can be amended as follows. A high-speed nozzle can be arranged atthe vicinity of roll C5, where the nozzle is able to deposit a band ofadhesive of small width, according to the sequence of the manufacturing,usually driven by the forming roll C3. A plurality of nozzles may beneeded.

Alternatively, a process known as offline process can be used. In such asituation, the bottom part of the cores are manufactured off-line (i.e.until roll C3 and C4, but before roll C5 (calendering), and then broughtonto the final manufacturing line in a perpendicular manner (the finalmanufacturing line being the line where the absorbent article or core isinserted into a diaper for example). Beads are applied and then the toplayer is applied. Calendering and cutting is then performed.

The process can be reversed, where the top layer and the bottom layersare swapped. It is also possible that pockets be formed in both layers;in such a case there will be two forming devices on the line.

A further embodiment is disclosed below, where the respective sheets areinverted. As mentioned above, the process can be reversed, where the toplayer and the bottom layers are swapped.

In this embodiment depicted at FIG. 12, the forming of the corrugationsis assisted with a counter-roll placed on top of roll C2. The counterroll CC2 and the roll C2 can be matched through a proper driving device.Said device can be gears, or a belt (notched or not). Alternatively, thematching can be simply obtained by friction, roll CC2 being free on itsaxis.

This embodiment is used to further form the corrugations, by pinchingthe sheet between two facing, corresponding, surfaces of cooperatingrolls. This is represented on FIG. 12, where C2 and CC2 are representedaccording to a cross-section (along the longitudinal axis). As can beseen, roll CC2 comprises ribs 81 a, 81 b, 81 c, 81 d cooperating withthe grooves 71 a, 71 b, 71 c, 71 d (only valley 72 a and peak 73 a arerepresented) of roll C2.

For this embodiment, the sheet 2 which is the one that is formed onrolls C2 and CC2 does not receive any adhesive coat in this situation,which enables the two rolls C2 and CC2 to interact and pinch the sheet2. The pockets will then be formed on this sheet 2 without the adhesiverather on the sheet 2 with the adhesive as in the previous embodiment.For this, the sheet 7 will receive the adhesive layer (3) and the beads(5), notably at the stage of roll C5 for example.

Apart from the inversion (and associated steps for the adhesivedeposition) and the additional steps for the counter roll CC2, theprocess is performed in substantially the same way.

The absorbent article or absorbent core of the invention can be used ina variety of products. It may be associated with a layer of fluff orcellulose layer, an acquisition/distribution layer, or both; it can alsobe used stacked one over the other in 2 or more layers, where thepatterns of pockets may be aligned or offset, and the like, creating 3Ddraining network. The absorbent article or core of the invention cangenerally speaking be used as part of personal care products, especiallydiapers.

1. A process for manufacturing an absorbent article (1), said articlecomprising: a first sheet layer (2) presenting an array of absorbentreceiving pockets (4, 4 a); masses (6) of superabsorbent material, whichmasses are placed in said absorbent receiving pockets (4, 4 a); a secondsheet layer (7) placed on top of the first layer; said processcomprising the steps of providing a first sheet layer (2); conformingsaid first layer on a first roll C2, whereby longitudinal corrugationsare formed on the layer; conforming said corrugated layer (2) on asecond roll C3, said second roll C3 comprising recesses (91 a, 91 b, 91c) corresponding to the array of absorbent receiving pockets (4, 4 a),whereby a pattern of pockets (4, 4 a) is obtained; providing apre-metered amount of SAP particulate material (6); providing a secondsheet layer (7) material and affixing it for sandwiching with the firstsheet layer; finishing the absorbent article, and said step ofconforming on a first roll C2 being obtained by friction of the sheetlayer (2) on the corresponding corrugated surface of said roll C2
 2. Theprocess of claim 1, further comprising unrolling sheet layer (2) fromroll C1, where roll C2 has a rotating speed (peripheral) that is 5 to20% above the speed of roll C1.
 3. The process of claim 1, furthercomprising the step of unstressing the sheet between rolls C2 and C3. 4.The process of claim 3; where roll C1 has a rotating speed which ishigher than the rotating speed of roll C3, where roll C1 has a rotatingspeed (peripheral) that is 5 to 20% above the speed of roll C3.
 5. Theprocess of claim 1, further comprising the step of pinching the sheetbetween roll C2 and counter roll CC2, where the roll C2 and counter rollCC2 have grooves (71 a, 71 b, 71 c, 71 d) and ribs (81 a, 81 b, 81 c, 81d) cooperating with each other.
 6. The process of claim 1, wherein thestep of forming the pockets comprises holding the layer (2) and/or (7)into the second roll C3 by applying vacuum.
 7. The process of claim 1,wherein said pre-metered amount of SAP material is delivered from adelivering unit placed above roll C3, whereby the pre-metered amount ofSAP is filled in a pattern of pockets.
 8. The process of claim 1,further comprising the step of: providing bonding beads (5), preferablyadhesive beads, between the pockets.
 9. The process of claim 1, furthercomprising the step of: providing adhesive layers (3) and/or (8) betweenthe first and second layers, whereby said layers are bonded.
 10. Theprocess of claim 1, further comprising the step of: calendering into theabsorbent article (1).
 11. The process of claim 1, wherein the sheetlayer (2) and/or (7) is/are non-woven.
 12. The process of claim 1,wherein the sheet layer (2) is impervious to liquids and the sheet layer(7) allows penetration of liquids into the masses of superabsorbentmaterial.
 13. A process for manufacturing a diaper, training pant,sanitary napkin, incontinence garment or bandage comprisingmanufacturing an absorbent article according to claim 1, and convertingsaid article into said diaper, training pant, sanitary napkin,incontinence garment or bandage.